1. Field
The present invention relates generally to radiation treatment, and more particularly to calibrating systems to be used during such treatment.
2. Description
Conventional radiation treatment typically involves directing a radiation beam at a tumor in a patient to deliver a predetermined dose of treatment radiation to the tumor according to an established treatment plan. A suitable radiation treatment device is described in U.S. Pat. No. 5,668,847, issued Sep. 16, 1997 to Hernandez, the contents of which are incorporated herein for all purposes.
Healthy tissue and organs are often in the treatment path of the radiation beam during radiation treatment. The healthy tissue and organs must be taken into account when delivering a dose of radiation to the tumor, thereby complicating determination of the treatment plan. Specifically, the plan must strike a balance between the need to minimize damage to healthy tissue and organs and the need to ensure that the tumor receives an adequately high dose of radiation. In this regard, cure rates for many tumors are a sensitive function of the radiation dose they receive.
Treatment plans are therefore designed to maximize radiation delivered to a target while minimizing radiation delivered to healthy tissue. If the radiation is not delivered exactly as required by the treatment plan, the goals of maximizing target radiation and minimizing healthy tissue radiation may not be achieved. More specifically, errors in radiation delivery can result in low irradiation of tumors and high irradiation of sensitive healthy tissue. The potential for mis-irradiation increases with increased delivery errors.
To ensure that radiation will be delivered to a proper area, a light field is used to indicate the position of a field within which radiation will be delivered. In particular, light is projected onto a patient to create a light field and an operator determines whether the light field delineates an area to which radiation is to be delivered according to a treatment plan. Accordingly, the light field is assumed to be located at a same position as a radiation field within which radiation will be delivered during radiation treatment.
Delivery errors may occur if the light field is not located at a same position as the subsequently-produced radiation field. Accordingly, it is necessary to verify that the position of the light field accurately represents a position of the radiation field. Conventional verification procedures are time-consuming. Accordingly, an operator may verify congruence of the light field and the radiation field only at the beginning of each day. As a result, the operator is not aware if the light field and the radiation field have become misaligned at some point during the day and each subsequent patient during the day is exposed to the possibility of increased delivery errors.
Modern radiation therapy uses beam-shaping devices to produce radiation fields of various shapes. These radiation fields may be used to provide more precise treatment than otherwise available. In order to avoid irradiation of unintended targets by a shaped radiation field, an operator verifies that the beam-shaping devices are configured so as to produce a field shape that complies with a specified treatment plan. As described above, current procedures for verifying the configuration of beam-shaping devices are slow and therefore performed at unacceptable intervals, such as daily.
It would therefore be beneficial to provide efficient and effective verification of congruence between a light field and a radiation field used for radiation treatment, as well as verification of beam-shaping device configuration. When used in conjunction with conventionally-designed treatments, such verification could reduce the chance of harming healthy tissue. Such verification may also allow the use of more aggressive treatments than currently available.
To address at least the above problems, some embodiments of the present invention provide a system, method, apparatus, and means to acquire first electronic image data representing a phantom located at a first position and irradiated by a first radiation field emitted by a radiation emitter, acquire second electronic image data representing the phantom located at a second position based at least on a first light field emitted by the light emitter and irradiated by a second radiation field emitted by the radiation emitter, generate third electronic image data by correcting the second electronic image data based at least on the first electronic image data, and determine a deviation between the first light field and the second radiation field based at least on the third electronic image data.
In some embodiments, the present invention provides acquisition of first electronic image data representing a first radiation field emitted by a radiation emitter and shaped by one or more of multi-leaf collimator leaves in a first leaf configuration, movement of one or more of the multi-leaf collimator leaves from the first leaf configuration, movement of one or more of the multi-leaf collimator leaves to a second leaf configuration, acquisition of second electronic image data representing a second radiation field emitted by a radiation emitter and shaped by one or more of the multi-leaf collimator leaves in the second leaf configuration, generation of third electronic image data by correcting the second electronic image data based at least on the first electronic image data, and determination of a deviation between the first radiation field and the second radiation field based at least on the third electronic image data.
The present invention is not limited to the disclosed embodiments, however, as those of ordinary skill in the art can readily adapt the teachings of the present invention to create other embodiments and applications.